Calculate Savings Bonds

Estimate the future value of your Series I or Series EE Savings Bonds

Series I (Inflation-Protected) Series EE (Fixed Rate)

Projection Results

Total Value at Maturity:

Total Interest Earned:

Composite Annual Rate:

*Note: Series EE bonds are guaranteed to double in value if held for 20 years, regardless of fixed rates.

Understanding US Savings Bonds

Savings bonds are debt securities issued by the U.S. Department of the Treasury to help pay for the federal government's borrowing needs. They are considered one of the safest investments because they are backed by the full faith and credit of the United States government.

Series I vs. Series EE

Series I Bonds: These are designed to protect your purchasing power. The interest rate is a "composite rate" consisting of a fixed rate that stays the same for 30 years and a semiannual inflation rate that changes every six months based on the Consumer Price Index (CPI-U).

Series EE Bonds: These carry a fixed interest rate. However, the most significant feature of Series EE bonds issued since May 2005 is the Treasury's guarantee that the bond will double in value if held for exactly 20 years. If the fixed rate doesn't get it there, the Treasury makes a one-time adjustment to fulfill that promise.

Example Calculation

If you purchase a Series I Bond for 1,000 units with a 1.0% fixed rate and an estimated 3.0% annual inflation rate:

• The composite rate is calculated as: Fixed Rate + (2 x Semiannual Inflation) + (Fixed x Semiannual Inflation).
• Over 20 years, compounding semiannually, your bond would grow significantly beyond its initial face value.
• Remember: Savings bonds must be held for at least 1 year, and if cashed before 5 years, you lose the last 3 months of interest.

Taxation and Interest

Interest on savings bonds is subject to federal income tax but exempt from state and local taxes. You can defer reporting the interest until you cash the bond or it reaches final maturity at 30 years. In some cases, if used for higher education expenses, the interest may be federally tax-exempt.

function toggleInflationInput() { var series = document.getElementById("bondSeries").value; var container = document.getElementById("inflationContainer"); if (series === "EE") { container.style.opacity = "0.3"; document.getElementById("inflationRate").disabled = true; } else { container.style.opacity = "1"; document.getElementById("inflationRate").disabled = false; } } function calculateBondValue() { var series = document.getElementById("bondSeries").value; var principal = parseFloat(document.getElementById("purchaseAmount").value); var years = parseFloat(document.getElementById("yearsHeld").value); var fixed = parseFloat(document.getElementById("fixedRate").value) / 100; var inflation = parseFloat(document.getElementById("inflationRate").value) / 100; if (isNaN(principal) || isNaN(years) || isNaN(fixed)) { alert("Please enter valid numbers for principal, years, and fixed rate."); return; } var compositeRate; var finalVal; var eeNote = document.getElementById("eeNote"); eeNote.style.display = "none"; if (series === "I") { if (isNaN(inflation)) { inflation = 0; } // I-Bond Composite Rate Formula: [Fixed + (2 x Semiannual) + (Fixed x Semiannual)] // We use annual inflation / 2 for semiannual calculation var semiannualInflation = inflation / 2; compositeRate = fixed + (2 * semiannualInflation) + (fixed * semiannualInflation); // Semiannual compounding: A = P(1 + r/2)^(2t) finalVal = principal * Math.pow((1 + (compositeRate / 2)), (2 * years)); } else { // Series EE calculation compositeRate = fixed; finalVal = principal * Math.pow((1 + (compositeRate / 2)), (2 * years)); // Check if EE bond hits the 20-year doubling guarantee if (years >= 20 && finalVal 20) { var yearsAfterDouble = years – 20; finalVal = (principal * 2) * Math.pow((1 + (fixed / 2)), (2 * yearsAfterDouble)); } } if (years >= 20) { eeNote.style.display = "block"; } } var totalInterest = finalVal – principal; document.getElementById("finalValue").innerText = "$" + finalVal.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("interestEarned").innerText = "$" + totalInterest.toLocaleString(undefined, {minimumFractionDigits: 2, maximumFractionDigits: 2}); document.getElementById("compositeRateDisplay").innerText = (compositeRate * 100).toFixed(2) + "%"; document.getElementById("bondResult").style.display = "block"; }